This invention relates to a variable reluctance, phase shift type position detection device and, more particularly, to a position detection device of this type capable of applicable, with a simple structure, to a linear guide mechanism such as a ball screw or a ball guide using ball bearings as their bearings.
A variable reluctance, phase shift type linear position detection device is disclosed in U.S. Pat. No. 4,556,886. The position detection device disclosed in this patent includes primary coils disposed in predetermined locations which are shifted in the direction of displacement, secondary coils provided in correspondence to these primary coils and a core section having cores disposed relatively displaceably to the secondary coils and with a predetermined interval in the direction of displacement. The respective primary coils are individually excited by reference ac signals which are shifted in phase from one another whereby output signals which are the reference ac signals phase-shifted in accordance with the position of the core section relative to the primary coils are produced from the primary coils.
If the above described linear position detection device is used for a linear guide mechanism such as a ball screw or a ball guide having ball bearings as their bearings, it is necessary to provide, in addition to the linear guide, a core section including a plurality of cores extending in parallel with the linear guide. This requires a considerable extra space with resulting difficulty in achieving a compact design and resulting complex structure and high manufacturing cost.